Means for synchronizing a speed-following machine in relation to a speed-setting machine

ABSTRACT

When two machines are working in tandem to perform successive working on a component there is an obvious need for synchronizing the running of the two machines, so that the second one is prepared to receive the component, when the first machine has terminated its working step thereon. An exact timing of the operation is obtained if the second machine is driven hydraulically and the conduits conveying the pressure fluid included a governing valve having two rotatable members, each driven by one of the machines and the conduits further include a solenoid valve, which is governed by signals from an indicating switch, likewise having two members, each driven by one of the machines. The governing valve determines the amount of hydraulic fluid supplied to the second machine and the indicating switch ensures that the conduits are open only within a selected range of angular displacement between the two machines.

United States Patent Liljeqvist et al.

Feb. 27, 1973 MEANS FOR SYNCHRONIZING A SPEED-FOLLOWING MACHINE IN RELATION TO A SPEED-SETTING MACHINE Inventors: Alf Harald Liljeqvist, 260 44 Mjohult; Folke Liedholm, Havertgatan 33, Halsingborg, both of Sweden Filed: June 28, 1971 Appl. No.: 157,131

US. Cl. ..91/412, 60/97 E Int. Cl ..FlSb 11/22 Field of Search ..60/97 E, 97 S; 91/412, 171

References Cited UNITED STATES PATENTS 4 1910 Coyle ..91 171 x 8/1945 Kopp ..91 171 Primary ExaminerEdgar W. Geoghegan Attorney-Holman & Stern 5 7 ABSTRACT When two machines are working in tandem to perform successive working on a component there is an obvious need for synchronizing the running of the two machines, so that the second one is prepared to receive the component, when the first machine has terminated its working step thereon. An exact timing of the operation is obtained if the second machine is driven hydraulically and the conduits conveying the pressure fluid included a governing valve having two rotatable members, each driven by one of the machines and the conduits further include a solenoid valve, which is governed by signals from an indicating switch, likewise having two members, each driven by one of the machines. The governing valve determines the amount of hydraulic fluid supplied to the second machine and the indicating switch ensures that the conduits are open only within a selected range of angular displacement between the two machines.

SHEET 30F 4 FIG. 3

FIG. -4

MEANS FOR SYNCHRONIZING A SPEED- FOLLOWING MACHINE IN RELATION TO A SPEED-SETTING MACHINE BACKGROUND OF THE INVENTION The present invention relates to means for synchronizing a speed-following machine in relation to a speed-setting machine.

Previous proposals for this purpose have for instance included a differential gear, which, however, suffers from certain disadvantages i.e. that the synchronous position of the two machines will vary considerably at different speeds. If the load on the speed-following machine exceeds the capacity of its driving motor, there must be means to by-pass the differential gear, as this would be damaged if not properly designed to transfer power from the speed-setting machine to the speedfollowing machine. A further disadvantage is that the whole system will easily be subjected to oscillations during rapid changes of the speed.

Electric signal producing members have also been proposed, which have been located at the speed-setting as well as at the speed-following machine and have monitored the synchronous position of its respective machine to govern the driving motor of the speed-following machine. The disadvantages of such systems, beside the high price and the obvious difficulties in locating possible damages and performing repairs, on the first hand is that the driving motor of the speed-following machine, which must be an electric one, is sensitive to variations in the load, especially at low speeds. It is also difficult to produce a large torque when starting.

SUMMARY OF THE INVENTION With hydraulic driving systems it is customary to have a governing valve in the supply and/or the return conduit. That is however, not satisfactory when two machines are required to run in an exactly synchronous position.

The present invention refers to a synchronizing means in a plant in which at least the speed following machine comprises a hydraulically driven component. The aim of the invention is to provide a simple and reliable apparatus, which without imposing any load on the machines, monitors the speed and the synchronous position of the speed-setting machine and maintains the speed of the following machine at such a value, that the synchronous position of the speed-following machine will only vary within a few degrees only.

According to the invention a governing valve is fitted into the conduits between the hydraulic driving motor of the speed following machine and the hydraulic pumping means, said governing valve having one member driven by the speed setting machine, and one member mechanically independent of the first mentioned member and driven in the same direction by the speed-following machine, said members, depending upon their relative position, governing the flow of hydraulic fluid. A solenoid valve is further fitted into the conduits, and an indicating switch supplies signals to the solenoid valve and comprises a first contact member driven by the speed-setting machine and a second contact member driven by the speed-following machine and further being so arranged that it emits a signal for bringing the solenoid valve into position to open the conduits in one relative position of the contact members only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows the hydraulic system between two working machines, according to one embodiment of the invention,

FIG. 2 shows a longitudinal section through a four way valve, forming part of FIG. 1

FIG. 3 shows a section along line III-III in FIG. 2,

FIG. 4 shows a section along line IV-IV in FIG. 2, and further, on a larger scale, a section through the four-way valve of FIG. 1, and

FIG. 5 shows a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The plant shown in FIG. 1 comprises a first speedsetting working machine 10 and a speed following machine 11. The first machine 10 performs a certain machining of a component, which later on is further machined in machine 11. Machine 10 may be provided with a feeding means and machine 11 with a corresponding receiver for the component transferred from machine 10. For this reason it is important that the angular displacement between the synchronous position of the machines is as small as possible.

The speed-following machine 11 is hydraulically driven, or contains a mayor component which is hydraulically driven. The driving power in this embodiment is obtained from an hydraulic motor 12 having a constant displacement, and being supplied with hydraulic fluid from a pumping means, generally denoted by 13, and comprising a pump 14 delivering fluid at constant pressure, but at a rate which may be automatically varied. The pressure conduit from the pump is denoted by 15a and 15b and the return conduit from the motor is denoted by 16b and 16a, respectively. Between the portions a and b, respectively, in the piping system a four-way valve 17 is fitted, which is designed to govern the supply of driving fluid.

This valve basically consists of an outer rotatable sleeve 18 provided with four openings 19, 20, 21 and 22, respectively, spaced in relation to each other, as well as a rotatable valve body 23 fitted inside the sleeve and having two lands 24 and 25, respectively. The valve member is mechanically independent of the sleeve insofar as it can turn freely in any direction within the same.

The sleeve 18 in this embodiment is driven clockwise by the speed-following machine 11, and a valve body 23 is likewise driven clockwise by the speed-setting machine 10. Opening 19 is connected to pipe 15a, opening 20 to pipe 15b, opening 21 to pipe 16a and opening 22 to pipe 16b.

In the relative position between the sleeve and the valve body shown in FIG. 1 (and in FIG. 4) a certain quantity of hydraulic fluid is supplied to the driving motor 12. If the speed-setting machine is retarded the speed-following machine can be operated only until the sleeve has turned sufficiently to cover the openings 19 and 21 by the lands 24 and 25, on which occasion the supply of fluid to the driving motor 12 is switched off (the position denoted by dash-dotted lines in FIG. 4). When the speed-setting machine 10 is accelerated the valve body 23 is rotated clock-wise and passage to the hydraulic motor 12 is again opened. Hereby the sleeve 18 will be further turned clock-wise, and the lands 24,

25 are brought into an equilibrium position in relation to openings 19 and 21, in such a manner that both machines will be run synchronously. If the speed of machine is increased the lands 24, and 25 will cover a smaller portion of openings 19 and 21, whereby the supply of driving fluid to the driving motor 12 is increased.

The lands 24 and 25 are preferably designed in such a manner that only a small angular change is required to bring about a completely closed, or a completely open passage, whereby the angular displacement between the machines due to variations in speed will be small. In order to obtain a smooth running of the driving motor 12, as well as of the speed-following machine, the land 25 ought to be somewhat broader than the opening 21 as compared to the relative size of the land 24 and the opening 19 (of FIG. 4). The return flow from the driving motor will thereby be restricted somewhat earlier than the supply conduit, whereby a certain back pressure is maintained in the return conduit. This aids in stabilizing the driving motor and balancing the valve body.

The shape of the four-way valve is shown in FIGS. 2-4. The sleeve 18 is mounted on a shaft 26, which is journaled in a housing 27 to which the conduits 15a, 15b and 16a, 16b, respectively, are attached, these pipes or conduits are, in a manner known per se, connected to axially separated peripheral grooves in the housing which cooperate with radial bores in the shaft and in the sleeve 18, respectively. Each bore is continued by an axial passage which ends in an opening 19 to 22 in the external envelope surface of the sleeve. A pinion 28 is connected to the sleeve and is driven in any suitable manner from the speed-following machine. The valve body 23 is rotatably journaled in the sleeve, and a second pinion 30 is mounted on a shaft 29 extending from the valve body. This pinion in a. suitable manner is driven by the speed-setting machine. The rotating parts are provided with suitable bearings and sealing means. The operation of the connections within the valve are of conventional type, and need not be explained in detail here.

In order to prevent the two machines from operating in a position which is turned 180 from the desired synchronous position, i.e. in a position where land 24 would cooperate with opening 21, an indicating switch 31 is provided. This comprises a first contact member 32, which rotates synchronously with the speed-setting machine 10, and a second contact member 33 rotating synchronously with the speed-following machine 11. Electric current can only pass to a solenoid valve 34 fitted in the conduit 15a, 16a, when these contact members have the proper relative position, whereby it is possible to bring machine 11 into operation. By suitably designed relays it is possible to permanently switch off the supply of current to the solenoid valve 34 if the speed-following machine 11, due for instance to a overload thereof, and consequently the corresponding member in the indicating switch should be brought out of its synchronous position. The speed-following machine 10 will then be stopped without influencing, or being influenced by, the speed-setting machine.

The hydraulic circuit may of course include valves which make it possible to operate the speed-following machine completely independent of machine 10, and if the hydraulic motor is designed in the appropriate manner the whole system may be reversible.

FIG. 5 shows a simplified version of the arrangement according to FIG. 1 as utilized with non-reversible machinery.

The speed-setting machine is denoted by 10 and the speed-following machine by 11. The hydraulic driving motor 12 is supplied with driving fluid from a pump 14 drawing from a receptacle l3 and feeding the fluid by way of conduit 15 to the motor, from which it is returned by way of conduit 16.

The solenoid valve 34 is fitted into both conduits, but the governing valve 40 in this embodiment is only connected to the return conduit 16. The governing valve comprises an inner valve body 41, driven by the speed setting machine 10, and an outer sleeve 42 driven by the speed-following machine. The sleeve is provided with two openings 43 and 44, and the valve body 41, which is a solid cylinder, is provided with a diametrically running passage 45. The latter is somewhat wider at the end intended to cooperate with opening 43. It is evident that the position of the openings to the passage in relation to the openings in the outer sleeve will determine the amount of fluid flowing through the governing valve.

The indicating switch 31 is of the same type as described in connection with FIG. 1, and contains contact members 32 and 33 driven by the speed-setting and the speed-following machine, respectively.

What we claim is:

1. Means for synchronizing a speed-following machine in relation to a speed-setting machine, of which at least the former comprises a hydraulically driven component supplied with pressure fluid from a pumping means, in which a governing valve is fitted in conduits between the hydraulic driving motor of the speed-following machine and the hydraulic pumping means, said governing valve having one member driven by the speed-setting machine, and one .member mechanically independent of the first mentioned member by the speed-following machine, said members depending upon their relative position governing the flow of hydraulic fluid flowing through a solenoid valve in said conduits, and an indicating switch supplying signals to the solenoid valve and comprising a first con tact member driven by the speed-setting machine and a second contact member driven by the speed-following machine and further being so arranged that it emits a signal for bringing the solenoid valve into position to open the conduits in only one relative position of the contact members.

2. The means according to claim 1 in which the governing valve is a four-way valve.

3. The means according to claim 2, in which the fourway valve comprises a rotatable sleeve, driven by the speed-following machine, and mounted in a stationary housing having four attachments, as well as a valve member having two lands rotatably mounted inside said sleeve and driven by the speed setting machine.

4. The means according to claim 3, in which the land cooperating with an outlet attachment is broader than the land cooperating with an inlet attachment. 

1. Means for synchronizing a speed-following machine in relation to a speed-setting machine, of which at least the former comprises a hydraulically driven component supplied with pressure fluid from a pumping means, in which a governing valve is fitted in conduits between the hydraulic driving motor of the speedfollowing machine and the hydraulic pumping means, said governing valve having one member driven by the speed-setting machine, and one member mechanically independent of the first mentioned member by the speed-following machine, said members depending upon their relative position governing the flow of hydraulic fluid flowing through a solenoid valve in said conduits, and an indicating switch supplying signals to the solenoid valve and comprising a first contact member driven by the speed-setting machine and a second contact member driven by the speed-following machine and further being so arranged that it emits a signal for bringing the solenoid valve into position to open the conduits in only one relative position of the contact members.
 2. The means according to claim 1 in which the governing valve is a four-way valve.
 3. The means according to claim 2, in which the four-way valve comprises a rotatable sleeve, driven by the speed-following machine, and mounted in a stationary housing having four attachments, as well as a valve member having two lands rotatably mounted inside said sleeve and driven by the speed setting machine.
 4. The means according to claim 3, in which the land cooperating with an outlet attachment is broader than the land cooperating with an inlet attachment. 